The invention relates to a coffee machine comprising a boiling chamber, two pistons adjustable independently of each other and adapted to be pushed into the boiling chamber from opposite sides and defining between them a boiling space to hold and boil a predetermined quantity of powdered coffee, a source of boiling water with a through-flow heater and a boiling water pressure generator and a hydraulic actuating device for the pistons with a pressurised medium circuit comprising a pressurised medium pump.
Conventional coffee machines of this type use their own boiling water pump as a means of generating boiling water pressure. This solution is relatively complicated both in terms of prime cost of the coffee machine and also in terms of the space required. Furthermore, such pumps are subject to a certain wear and tear, particularly if the water contains a high level of lime.